The Video-Gaming Scale for Adolescents (VGS-A): An Item Response Theory analysis of Differential Item Functioning across age.

As youth use video-games from a very early age till to young adulthood, it is important to have a measurement tool able to equally assess pathological gaming behavior in adolescents of different ages. The aim of this study was to verify the measurement invariance across age of the Video-Gaming Scale for Adolescents (VGS-A; Donati, Chiesi, & Primi, 2014), a brief scale recently developed to assess pathological video-gaming among adolescents referring to the DSM-5 (American Psychiatric Association, 2013). Specifically, we aimed at investigating Differential Item Functioning across age by applying Item Response Theory (IRT) analyses. Participants included 1681 adolescents (57% males, mean age= 15.6 years, SD =1.8) attending junior high school and high school in Italy. Two groups were created dividing the whole sample into younger (from 12 to 15 years of age) and older (from 16 to 21 years of age) respondents. IRT analyses for polytomous, ordered response category were applied. Preliminarily, the unidimensionality of the scale was verified in both the groups of participants. Then, the equivalence of the items across age was assessed by analyzing Differential Item Functioning across the two age groups. The DIF analysis revealed that no item displayed a significant difference, attesting that the VGS-A could be considered equivalent across age. Future studies might analyze the cross-cultural invariance of the VGS-A in order to investigate if the items are metrically equivalent across different countries. In sum, by using IRT analyses, these findings showed that the VGS-A is invariant across age.